Researchers at Rutgers have suggested that topical caffeine may help lower the risk of UV-induced skin cancer. The research team found that caffeine inhibits ataxia telangiectasia and Rad3-related (ATR) kinase, a protein enzyme in the skin, thereby protecting against some cancers.

According to the study, while research has been done on protection from UV-induced cancers with orally administered caffeine, the mechanism behind its action has not yet been studied.

In their study, funded by the National Institutes of Health, the researchers note, "Suppression of ATR, or its downstream target checkpoint kinase 1 (Chk1), selectively sensitizes DNA-damaged and malignant cells to apoptosis. Agents that target this pathway are currently in clinical trials. Conversely, inhibition of other DNA damage response pathways, such as ataxia telangiectasia mutated (ATM) and BRCA1, promotes cancer."

The Rutgers team collaborated with researchers from the University of Washington to genetically modify and diminish the levels of ATR in one group of mice. They found that the genetically modified mice developed tumors more slowly than the unmodified mice, had 69% fewer tumors than regular mice and developed four times fewer invasive tumors. When caffeine was topically applied to the regular mice, they had 72% fewer squamous cell carcinomas, a form of skin cancer.

Based on their findings, the researchers hypothesize that topically applied caffeine may help prevent damaging UV light from causing skin cancer. However, the researchers also found that when both groups of mice were exposed to chronic UV rays for an extended period of time, tumor development occurred in both the genetically modified and regular mice. Therefore, they concluded that ATR inhibition is more efficacious before UV-induced skin cancers develop.

As this study suggests, perhaps caffeine should be formulated in sunscreens to increase skin protection against UV-induced skin cancer.